1492829-56-7Relevant academic research and scientific papers
Base-mediated chemo- and stereoselective addition of 5-aminoindole/ tryptamine and histamines onto alkynes
Verma, Akhilesh K.,Patel, Monika,Joshi, Megha,Likhar, Pravin R.,Tiwari, Rakesh K.,Parang, Keykavous
, p. 172 - 186 (2014)
Transition-metal-free chemo- and stereoselective addition of 5-aminoindole (1a), tryptamine (1b), and histamine (1c) to alkynes 2a-s to synthesize the indolyl/imidazolyl enamines 3a-p, 5a-o, and 6a-e using superbasic solutions of alkali-metal hydroxides in DMSO is described. The addition of N-heterocycles onto alkynes takes places chemoselectively without affecting the 1 amino groups (aromatic and aliphatic) of 5-aminoindole, tryptamine, and histamine. The stereochemistry of the products was found to be dependent upon reaction time; an increase in reaction time leads to the formation of a mixture of E/Z isomers and the thermodynamically stable E addition product. The chemoselective addition of N-heterocycle 1a onto alkyne over thiophenol 7 and phenol 8 is supported by control experiments. Competitive experiments showed that 5-aminoindole was more reactive than tryptamine, and histamine was found to be the least reactive. The present methodology provides an efficient chemoselective method to synthesize a variety of (Z)-enamines of 5-aminoindole, tryptamine, and histamine without affecting the 1 amino group. The presence of the free amino group in enamines could be further used for synthetic elaboration, which proved to be highly advantageous for structural and biological activity assessments.
